1. Technical Field
The present invention relates to stereo image display device and method.
2. Related Art
An image viewed through the right eye of a human and an image viewed through the left eye of the human are combine with each other in the brain of the human, whereby the human recognizes the viewed object as a stereo image. This is possible because the same object is viewed at different angles (i.e., from different positions) by the right and left eyes and thus the image viewed by the right eye and the image viewed by the left eye are slightly different from each other.
Therefore, in order to make a viewer recognize a two-dimensionally displayed image as a stereo image, a parallactic image comprising an image to be viewed by the right eye (right-eye image) and an image to be viewed by the left eye (left-eye image) is displayed on the two-dimensional plane, and only the right-eye image is made to reach the right eye of the viewer while only the left-eye image is made to reach the left eye of the viewer, whereby the viewer can recognize the two-dimensional parallactic image as a stereo image.
Specifically, a stereo image display device is equipped with an image display unit for displaying a parallactic image on a display plane, and a parallactic image selecting unit for making only the right-eye image of the parallactic image reach the right eye of a viewer and making only the left-eye image of the parallactic image reach the left eye of the viewer. A pair of glasses may be used as the parallactic image selecting unit, for example. The viewer puts on the glasses concerned to thereby recognize a stereo image. As the glasses may be generally used polarized glasses having right-eye and left-eye transmissible portions that transmit therethrough polarized light beams of different polarization directions, or liquid crystal shutter glasses having right-eye and left-eye transmissible portions that are alternately varied between a transmissible state and a non-transmissible state. In the case of use of the polarized glasses, the right-eye image of the parallactic image is set to be based on the polarized light having the polarization direction along which the right-eye transmissible portion transmits light, and the left-eye image of the parallactic image is set to be based on the polarized light having the polarization direction along which the left-eye transmissible portion transmits light, whereby only the right-eye image is made to reach the right eye of the viewer and only the left-eye image is made to reach the left eye of the viewer. Furthermore, in the case of use of the liquid crystal shutter glasses, the right-eye image of the parallactic image is displayed under the state that the right-eye transmissible portion is set to the transmissible state and the left-eye transmissible portion is set to the non-transmissible state, and the left-eye image of the parallactic image is displayed under the state that the right-eye is set to the non-transmissible state and the left-eye transmissible portion is set to the transmissible state, whereby only the right-eye image is made to reach the right eye of the viewer and only the left-eye image is made to reach the left eye of the viewer.
Furthermore, there is known a stereo image display device using a lenticular lens as a parallactic image selecting unit. Specifically, a lenticular lens is disposed on a display plane so that only the right-eye image of a parallactic image displayed on the display plane is guided to the right eye of a viewer, and only the left-eye image of the parallactic image displayed on the display plane is guided to the left eye of the viewer.
The stereo image display devices described above are disclosed in JP-A-63-70284 or JP-A-63-227193, for example.
In the stereo image display devices as described above, a viewer is made to view a stereo image which does not actually exist, and thus the viewer's convergence and the focal point are not coincident with each other, so that the viewer feels uncomfortable and suffers eye fatigue.
Particularly, when the viewer views a stereo image for a long time, a large load is imposed on the viewer's eyes and the eye fatigue is intensified.